The invention relates to an apparatus for the chip-removing processing of logs for the production of sideboards and/or wood chips with tools executed as circular saws and/or knife heads which have cutting edges distributed on the circumference, whereby two tools each are arranged with rotation axes that are parallel to each other and are driven in opposite rotation senses.
For the production of wood chips from side parts of logs transported in longitudinal direction, which can be round timber logs or already two-sidedly flattened modules, knife heads are used with rotation axes disposed transversely to the longitudinal direction of the wood. The sawing off of the sideboards is carried out in a known apparatus (DE-PS No. 29 28 949) with double circular saws, both circular sawblades of which are arranged with rotation axes parallel to each other and at the same time displaced in the longitudinal direction of the wood with respect to each other so that the cutting lines produced by the two circular saws overlap when viewed in the longitudinal direction of the wood without the circular saws touching one another. It is also known how to arrange the circular saws used to saw off the sideboards directly on the shaft of the knife heads and in axial distance to these (DE-OS No. 29 47 190). In this case the whole depth of cut has to be cut by only one circular sawblade which must have a correspondingly large diameter.
When only one knife head is used on each side of the log to produce the wood chips, strong unilateral forces are applied to the log, especially at the log beginning during engagement of the knife heads which make necessary an expensive guiding of the log. The diameter of the knife heads has to be chosen in such a way that the front side of the knife heads is in any case larger than the largest created width of the lateral surface of the log.
Even when so-called double circular saws are used, the force application is unilateral, when the log comes in, because one of the two circular saws by necessity engages the log earlier than the other circular saw. Because the circular saws that engages the log first cuts on a part of the wood in fiber-longitudinal direction, relatively long, stringlike fibers are created which cannot be screened out and which therefore cause considerable difficulties during the separation of the wood chips from the sawdust.
It is therefore the object of the invention to design an apparatus of the initially described type in such a way that as small as possible unilateral forces occur during the processing of the sides of the logs and that no long fibers are produced during the sawing process.
This object is attained according to the invention, in that the flight circles of the two tools overlap each other, the cutting edges of each tool engage into the gaps between the cutting edges of the respective other tool without touching, and both tools are driven in a forced synchronous run.
The two tools working in pairs (knife heads or circular saws) intermesh with their cutting edges in the work area. Therefore the two tools can be arranged at the same height and come into engagement simultaneously at least in the case of the regularly shaped logs. The forces occurring on both tools which are not directed in the longitudinal direction of the wood compensate each other. The overlap of the two tools occurs in the circumferential zone in which the cutting edges cut approximately in the longitudinal direction of the wood. If the two tools are circular saws, the formation of long fibers is prevented at this location, because the cutting edges of the two adjacent circular saws come into engagement alternatingly. Therefore, sawdust is also created in this region which can be sifted away without difficulty.